Vat dyeing of cellulose acetate



Patented Aug. 17, 1954 2,686,707 VAT DYEINGOF .CELLULOSE ACETATE Henry Charles Olpin and Tom Jacksonrsipondon,

l near Derby, England, assignors .neseLimited, a corporation of to British pen-1 Grea'tBrita'in No Drawing. Application April 14, 1951, Serial No. 221,125

.Claims priority, application Great Britain May 4, 1950 3 Claims.

"This invention relates to uniform or local co'louration of textile materials more particularly textile materials consisting of or containing fibres of cellulose acetate or .other cellulose ester or ether.

It has long been the practice to colour .cellulose textile .materialfe. .g. fabrics, with vat dyes by applying the unreduced vat dye in conjunction with ,a formaldehyde sulphoxylate and an alkali such as sodium or potasiumcarbonate, and thereafter steaming the material and subjecting it to oxidation. Thisfmethod, while very suc cessful "for cellulose textile materials yields but indifieren't results when applied to a textile .material of cellulose acetate .fibres. Unless the conditions are such that very substantial saponification o'fthe material takes place, the-fixation of the dye is very poor and thesresulting colourations are of low resistance to rubbing. By including a thiocyanatetin the mixture of lvat dye, formaldehyde sulphoxylate and alkali, some improvement infastness to rubbing can be obtained, but the disadvantage remains that the .material undergoes a considerable degree ofsaponifica-tion.

We have now found that excellent colourations of very good resistance to rubbing can be obtained with little or no saponification of the material by impregnating the material with an unreduced vat dye, an aldehyde sulphoxylate, a hydroxy-alkylamine anda thiocyanate, and thereafter steaming the material and subjecting it to oxdiation to reoxidiseto the parent vatdye the'leuco compound thereof produced and fixed onthe-material upon steaming, Preferably the dye, aldehyde-sulphoxylate, hydroxy alkylamine, and thiocyanate are applied together in an aqueous medium which may be applied over the whole surface of the fabric or locally according to the effect required. Very good results can belobtained with indigoid vat dyes and with very many :anthracene vat dyes. The colouratioris are not only of-good resistance to rubbing asindicated above,'but possess also "the excellent fastness to light and washing normally associated'with .colourations produced on cellulose textiles bymeans of vat dyes.

Thehydroxy alkylamine may be of the type NR1R2R3 wherein R1 is hydroxy-alkyl (.e. g. hydroxy-ethyl or hydroXy-iDropyl) R2 is hydrogen, hydroxy-alkyl, unsubstituted alkyl, cycloalkyl, or aralkyl, and R3 is hydrogen, hydroxy-alk-yl, unsubstituted alkyl, cycloalkyl, or aralkyl. Examples of suitable hydroxy-salkylamines are mono-, diand tri-ethanolamine, mono-, diand trirpropanolamine, hydroxyethyl -diethylamine, hydroxyethyl ethylamine, ,cyclohexyl-diethanolamine, 'cyclohexyl monoethanolamine, and benzyl-hydroxyethyl-amine. Monoethanolaminehas been found :of particular advantage in that when material uniformly or looally impregnated with the dye compositions is dried (as is usually desirable .ibefore zthe steaming :operation) it does not become tacky asis the case when triethanolamine, :for :example, "isused place of the monoethanolamine.

The proportion of alkylolamine may be from 5-,25% by weight .'of the dye composition -em ployed. The optimum proportion depends on the particular :hydroxy alkylamine employed and the particular vat :dye. For example, in the case ofindigoid vat .dyes the proportion maybe from 545% for example 110% of monoethanolamine or a slightly greater proportion of triethanolamine say, 151%. IInthGIGELSE-Of many anthraquinone vat ,dyes rather higher proportions of hydroxy alkylamine areladesirable, forexample, from 15-25% ;by weight 10f ztherdye composition. Using by Weight of :monoethanolamine very .good results [can the obtained with .a wide range of vat dyes. :Such high proportion 1111 general leads to a slight saponification of the material which may be reduced or avoided by reducing the proportion of monoethanolamine to, say, 15% by weight of the cdyeicomposition.

From the point -;of wiew .OfzCDSt of materials part of the hydroxyealkylamme imay advantageously be replaced :by about one "third of its weight .of sodium carbonate snot-her alkali-metal carbonate. The content of hydroxyralkylamine should not however-be less thamabout 51% or 5%.. Thus the material may beimpregnated'with a dye composition containing at .:least 41% nOf the hydroxyalkylamine together with :an alkali-metal carbonate, thesum of the percentage of the hydroxy-alkylamine andtthreeltimes the percentage of alkali-metal carbonate being from 1.0 to 25. In the CfizSBxQf :using'an :indigoid vat tdye thesum may be for A-instance from 10 to 20 while in the case of using an anthraguinonevat dye the sum may advantageously be from 15 to 2,5.

. As the vthiocyanate an alkali metal .or ammonium :thiocyanate is preferred, although the :use of-,other water-soluble thiocyanates, for example, alkaline .earth -or 1-zinc thiocyanates is not excluded fromthe scope of the invention. Sodium or potassium thiecyanate :is preferred.

The aldehyde.sulphoxylateremployed is preferably a formaldehyde sulphoxylate, particularly sodium formaldehyde rsulphoxylate. These .aldehyde sulphoxylatesionlyibecomeactive reducing agents at fairly :high temperatures. :In our new process the steaming treatment provides the requisite ihigh temperaturesand it is at this stage that the rat dyereduced and fixed on the :material :the :reduced or leuco :form.

The aqueous dye compositions need to be suitably thickened for local application and some degree of thickening is generally desirable when the dye compositions are applied over the whole surface of a fabric, for example, by mechanical impregnation methods, e. g. padding or all over printing. British gum is a very suitable thickener for our purposes though other thickeners may be employed, for example gum tragacanth.

Additions to the dye compositions other than those indicated above are not in general desirable or necessary. However, we do not exclude the presence for instance, of other swelling agents for cellulose acetate, for example, organic liquid swelling agents such as diethylene glycol or thiodiglycol. An addition which has been found useful more particularly in the case of indigoid dyes is urea; this may be incorporated in the dye composition for instance, in a proportion of 5-l2%, e. g. Hygroscopic liquids such as glycerol are often beneficial.

When colouring fabrics consisting of or containing cellulose acetate fibres the dye composition may be applied over the whole surface of the fabric, for example by padding or all-over printing, or it may be applied locally, for example by roller or screen printing methods. Although it is in general convenient to apply the dye and other components of the composition in the form of a single aqueous preparation, it is not essential. For example, the dye may first be applied to the material, e. g. as an aqueous dispersion and the material then dried before application of the remaining components in a separate operation.

The material carrying the dye and other components of the compositions is preferably dried prior to the steaming operation. The latter may be effected in the manner customary in the art of printing vat dyes .on textile materials. For the purposes of the present process a steaming of from 30-50 mins. at 104 C. has been found effective. This can be carried out for instance in a cottage steamer or in a continuous steamer. Substantially air-free steam is desirable.

The steamed material carries the vat dye in the leuco form and should be subjected to oxidation to convert the leuco compound to the parent vat dye. This may be effected conveniently by means of an aqueous solution of sodium perborate or percarbonate. Following the oxidation the material is preferably soaped, if desired after acidifying, and such soaping may be carried out with an aqueous soap solution at, say, 80 C. Higher temperatures are undesirable if delustring is to be avoided. The soaping may be replaced or supplemented by a steaming treatment. One purpose of the soaping and/or steaming is to cause the vat dye to exhibit its true shade as measured by the shade normally yielded on cellulose material.

The textile material coloured in accordance with the invention may be entirely of cellulose acetate fibres which may be present either as continuous filaments or as staple fibre. Textile materials containing cellulose acetate fibres in association with fibres of other materials, for example, animal fibres or natural or regenerated cellulose fibres may also be coloured by the new process. Mixed textile fabrics, for example, may be composed of cellulose acetate yarns in association with yarns of wool, silk, or other fibres. Again, the fabrics may consist of or contain yarns which contain both cellulose acetate staple fibres and fibres of other materials such as wool or cellulose.

By applying the dye compositions locally to 4 fabrics dyed with a dischargeable dye it is possible to obtain discharge effects due to the action of the aldehyde sulphoxylate under the influence of the steaming treatment.

The invention is illustrated by the following examples, the parts referred to being parts by weight.

Example I A cellulose acetate fabric is padded with the following composition:

Parts Durindone Blue 4 BCS (tetrabromindigo)--- 15 Formosul 10 Sodium thiocyanate l5 Monoethanolamine 10 Water I 25 British gum (30%) 15 Urea 10 A cellulose acetate fabric is printed with the following composition:

Parts Caledon Brilliant Purple 4 RPS (dichloroisodibenzanthrone) 2.5 Formosul l 10 Sodium thiocyanate 15 Monoethanolamine 20 British gum (30%) 40 Water 12.5

The material is then dried, steamed, oxidised and soaped in the manner indicated in Example I. A print of good colour value and good fastness to rubbing is obtained.

Similar results may be obtained by replacing the Caledon Brilliant Purple 4 RPS by any of the following dyes:

Caledon Yellow GS Flavanthrone Caledon Yellow 5 G Schultz, 7th edition, Supplementary vol. I, page 46, No. 1274a Caledon Yellow 2 R.

Caledon Yellow GKP Caledon Red FFS Schultz, 7th edition, No. 1221 Caledon Red BN Colour Index No. 1162 Caledon Brilliant Red 3 B Caledon Red Violet 2 RN Schultz, 7th edition,

Caledon Jade Green 4 GS Caledon Jade Green XS l2:12'-dimethoxydibenzanthrone Caledon Green 2 G Caledon Olive Green B product of ring closure of 13 (alpha anthraquinonylamino) benzanthrone Caledon Brown R 4:5-dibenzoylamino-1 :212 1'- dianthraquinone carbazole Caledon Ming Blue X an ether of 12:12'-dihydroxy-di-benzanthrone Caledon Dark Blue GS ethylene ether of 12:12-

dihydroxy-dibenzanthrone Caledon Dark Blue BM dibenzanthrone Example III A cellulose acetate fabric is padded with the following composition:

Parts Caledon Jade Green XS Formosul 10 Monoethanolamine 20 Sodium thiooyanate 15 British gum (30%) Water The padding is conducted so asto leave about 80% of the composition thereon, based on the weight of the material. The material is thereafter dried, steamed, oxidised and soaped in the manner described in Example I.

Similar results may be obtained by replacing the Caledon Jade Green XS by any of the following Caledon dyes:

Caledon Yellow GKP Brilliant Purple 4 RPS Cellulose acetate woven fabric is padded with this liquor so as to leave about 80% of the liquor thereon, based on the dry Weight of the fabric. The fabric is then dried, steamed twice for 15 minutes at 104-105 0., and oxidised and finished as described in Example I. A royal blue shade is obtained.

Example V A padding liquor is made up of Parts Caledon Brilliant Purple 4 RPS paste (I. C. I.) 10 Formosul 8 Sodium carbonate 6 Monoethanolamine 5 Sodium thiocyanate 15 Glycerine 3 Gum tragacanth (6%) 15 Water 38 Cellulose acetate is padded with this liquor, dried, steamed, and oxidised as described in Example IV to give a full purple shade of good fastness to rubbing.

The invention has been described more particularly with reference to the colouring of textile materials consisting of or containing cellulose acetate fibers; the new process may also be applied to textile materials consisting of or containing fibres of other cellulose esters of carboxylic acids or of cellulose ethers. Examples of such esters and ethers are cellulose acetate-propionate, cellulose acetate-butyrate, cellulose propionate, and ethyl benzyl cellulose.

According to a modification of the invention the hydroxy aliphatic amine may be replaced by another water-soluble primary, secondary, or tertiary amine base. Said bases should be of relatively low volatility, for example, of boiling point above C. so that they are substantially retained by the material at least up to the point at which steaming is efiected. As an example benzylamine may be mentioned.

Having described our invention, what we desire to secure by Letters Patent is:

1.. Process for the colouration of textile material comprising fibres of cellulose acetate, which comprises impregnating the material with an aqueous preparation containing an unreduced vat dye, a thiocyanate, sodium formaldehyde sulphoxylate, monoethanolamine and an alkali metal carbonate, the preparation containing at least 4% or" the monoethanolamine and the sum of the percentage of monoethanolamine and three times the percentage of alkali metal carbonate being from 10 to 25, and thereafter drying and steaming the material and subjecting it to oxidation to reoxidise to the parent vat dye the leuco compound thereof produced and fixed on the material by the steaming.

2. Process for the production of pattern effects on textile fabrics comprising fibres of cellulose acetate, which comprises printing the material with a thickened aqueous preparation containing an unreduced vat dye, a thiooyanate, sodium formaldehyde sulphoxylate, monoethanolamine and an alkali metal carbonate, the preparation containing at least 4% of the monoethanolamine and the sum of the percentage of monoethanolamine and three times the percentage of alkali metal carbonate being from 10 to 25, and thereafter drying and steaming the material and subjecting it to oxidation to reoxidise to the parent vat dye the leuco compound thereof produced and fixed on the material by the steaming.

3. A process for the colouration of textile material comprising fibres of cellulose acetate, which comprises impregnating the material with an aqueous preparation containing an unreduced vat dye, sodium formaldehyde sulphoxylate, from 5 to 20% of monoethanolamine and from 10 to 15% of sodium thiooyanate, the latter being the sole cellulose acetate swelling agent in the preparation, and thereafter drying and steaming the material and subjecting it to oxidation to reoxidise to the parent vat dye the leuco compound thereof produced and fixed on the material by the steaming.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,424,857 Scull July 29, 1947 2,524,072 Olpin Oct. 3, 1950 2,528,614 Seymour Nov. 7, 1950 2,574,806 Wiazmitinow Nov. 13, 1951 FOREIGN PATENTS Number Country Date 479,867 Great Britain Feb. 14, 1938 622,676 Great Britain May 5, 1949 

1. PROCESS FOR THE COLOURATION OF TEXTILE MATERIAL COMPRISING FIBRES OF CELLULOSE ACETATE, WHICH COMPRISES IMPREGNATING THE MATERIAL WITH AN AQUEOUS PREPARATION CONTAINING AN UNREDUCED VATDYE, A THIOCYANATE, SODIUM FORMALDEHYDE SULPHOXYLATE, MONOETHANOLAMINE AND AN ALKALI METAL CARBONATE, THE PREPARATION CONTAINING AT LEAST 4% OF THE MONOETHANOLAMINE AND THE SUM OF THE PERCENTAGE OF MONOETHANOLAMINE AND THREE TIMES THE PERCENTAGE OF ALKALI METAL CARBONATE BEING FROM 10 TO 25, AND THEREAFTER DRYING AND STEAMING THE MATERIAL AND SUBJECTING IT TO OXIDATION TO REOXIDISE TO THE PARENT VAT DYE THE LEUCO COMPOUND THEREOF PRODUCED AND FIXED ON THE MATERIAL BY THE STEAMING. 